FLTK and Xcode 4

Can anyone point me to some sort of guide for installing FLTK 1.3 for use with Xcode 4? I am having a lot of trouble. Currently, I am following the README that comes with FLTK 1.3, under the section for installing FLTK using Xcode 3. They don't have documentation for Xcode 4. Right now I am getting an error message

"The scheme 'clock' contains no buildables that can be built for the SDKs supported by the run destination My Mac 64-bit. Make sure your targets all specify SDKs that are supported by this version of Xcode."

which is apparently due to targeting an incompatible SDK. (Probably from using Xcode 4 to run an Xcode 3 project).

If anyone could either point me to a better source for installing FLTK with Xcode 4, or help me fix that error, that would be greatly appreciated.

I'm using fltk-1.3.0-source.tar.gz from fltk.org, which is the first URL attached, and the README from that package as a guide, which is the second URL.